Floating head for tube nests



Dec. 3, 1929. c. F. BRAUN 1,737,564

FLOATING HEAD FOR TUBE NESTS Original Filed Feb. 2, 1927 IN V EN TOR.

j BUY: lla ri'l' A TTORNEYS.

Patented Dec. 3, 1929 UNITED STATES PATENT OFFICE FLOATING HEAD FOR TUBE NESTS Application led February 2, 1927, Serial No. 165,320. Renewed September 3, 1929.

This invention relates to heat exchangers, stills, condensers and the like, and is particularly concerned with a floating head structure for such apparatus.

I In the construction of apparatus having a tubular shell, within which is mounted a tube nest and which nest is rigidly secured at one end of the shell, but allowed to float at its opposite end in order to accommodate expansion and contraction of the parts, it has been common practice to secure a cap over the tube sheet and to thereby form a floating head. In most of such structures the cap has been fitted with la relatively wide annular gasket which is interposed between it and the tube nest and through which the bolts extend. Due to this design, the effective free area of the tube nest is materially limited, thus decreasing the number of tubes which may be used in the nest with the result that the heat exchange surface is materially limited.

It is the object of the present invention to provide a simple arrangement whereby a larger amount of heat exchange surface may 2 be provided without increasing the dimensions of the shell or the tube sheet, and at the radial webs as 'indicated at 13 in Fig. 2 of the same time -insuring that the cap of the. floating head will be secured to the floating tube sheet in a manner to prevent leakage therebetween. The present invention contemplates the use of a tube sheet,` through which a plurality of tubes are extended and` over the area of which the tubes are arranged in symmetrical order, said tube sheet carrying a cap by which liquid .may be diverted from one group of'tubes to the next group. The cap is secured to the tube sheet by stud bolts; the bolts carrying individual gaskets and being surrounded by a ciredges of the cap and the tube nest.

The invention is illustrated by way of example in the accompanying drawings, in whichv e Fig. 1 is a fragmentary view of the end of a heat exchanger or the like showing the position of the iioating head wlthin the shell.

Fig. 2 is an enlarged fragmentary view, showing the arrangement of the tube nest and o'the bolts as viewed in the direction of the arcular gasketinterposed between the marginal v manner in which a tight joint is formed between the tube sheet and the cap.

Fig. 4 is a view drawn on a reduced scale showing the usual arrangement of tubes as contrasted with the novel arrangement disclosed in this application.

Referring more particularly to the drawings, 10 indicates the outer shell of the apparatus, which shell is closed at one end by a head 11. An outlet or inlet opening 12 is formed in the head onmay be formed in the shell if desired. In most apparatus of this character it is common practice to cause one fluid to flow lengthwise of the shell and another fluid to pursue a multi-pass flow' within the tubes of the tube nest. This is accomplished 'by arranging the tubes of the tube nest in'groups and insuring that the fluid within the tube nest will flow down one group of tubes and return in a counteriow along another group of tubes.`

In order to create this condition the caps at the ends of the tube sheet are formed with drawing. These webs are here shown as part of cap 14, ,although it will be understood that at the opposite-end of the shell (not shown) the tube nest is fixed to acap or drum having compartments communicating with various groups of tubes and also being fitted with induction and eduction pipes for creating a flow of fluid through the tube nest. f

As here shown it will be considered. that the tubes are divided into two groups, one. group being arranged above the longitudinal center line of the shell and generally indicated at A and the other group being arranged below the longitudinal center line of the shell and` being generally indicated at B. A fluid isde-l livered to the group A and flows in the direction of arrow c until it-reaches the compartment 15 formed by the cap '14 which `is fastened onto the end of the tube sheet 16. Here the fluid' will pass into the tubes of group B .and return to the eduction `port,as indicated by the arrow b.

As indicated in Fig. 2 of the drawlng the cap 14 is formed with the webs 13, a plurality yof which will divide the tubes into a number of smaller groups and will act, in combination with similar webs at the opposite end of the apparatus, to produce a larger number of passes of the fluid through the tubes. In any event it will be appreciated that a tight packing joint between the tube sheet 16 and the cap 14 is essential.

It has been common practice to form the caps with a bolting face, as shown at 17 in Fig. 2 of the drawing. This fact was deemed necessary in order that a gasket of similar Width' to the face might be interposedbetween the tube sheet 16 and the cap 14 and around the bolts.

By an examination of Figure 2 of the drawing, it will be seen that such a structure limited the available area in the tube sheet which might be occupied by tubes .and eliminated the possibility of using at least four of the tubes in the group of tubes shown between webs 13. Assuming that the group between the webs 13 represents one-sixth of the area of the tube sheet, it will be apparent that twenty-four tubes will be lost by using the wide clamping face on the cap 14, as indicated at 17 in Fig. 4. By the present arrangement this increased number of tubes could be placed in a piece of apparatus having a shell of identical diameter and without. altering the tube sheet other than to perforate it for the additional tubes. This is done by forming the cap 14 with a clamping face, as indicated at 18 in Figs. 2 and 3. This face is disposed outside of the row of stud bolts 19, which bolts are screwed into blind threaded openings, 20, in the outer face of the tube sheet 16. The outer,I ends of these bolts are threaded to receivecastle nuts. Annular gaskets, 22, are mounted upon the bolts and are seated upon suitable bosses, 23, Where they are held in clamp positions by the castle nuts.

By this arrangement, it is possible to completely seal the compartment 15 between the tube sheet 16 and the cap 14 by the relatively narrow gasket 18 which extends completely around the face of the tube sheetand the plurality of smaller annular gasket washers, 22, interposed between the bosses 23 and the nuts 21. This permits the clamping face to be reduced from thewidth indicated at 17 in Figure 4 to the width indicated by solid lines at 18 in Figure 2, and thus clears away a considerable amount of material whichY would obstruct the How of fluid from the ends of the tubes Y, X, Y and Z', now making it possible to use these tubes and to obtain an.

without departin from the spirit of my invention as descri ed.

Having thus described my invention, what I claim and desire to secure by Letters Patent isi 1. In a device of the character described, a iloating head for tube nests comprising a tube sheet through which a plurality of tubes extend, fastening bolts carried by the tube sheet and extending from the outer face thereof near they circumferential edge, an annular gasket disposed against said outer face and around the circle of bolts, a concaved-convexed cap disposed against the end of said tube sheet and havin a clamping edge outside the bolt line bearing against the annular gasket, said cap having openings through which the bolts extend, a plurality of gasket washers, one disposed on each of said bolts outside thecap, and blind nuts secured onto the ends of the bolts for fastening the cap to the tube sheet and for clamping the gaskets in position.

2. In a device of the character described, a shell having a tube nest therein, a floating tube sheet through which the tubes of said nest are fixed, said tube sheet bein of a smaller diameter than the shell, a eating head of substantially the same diameter as the tube sheet andsecured against the end face .shell having a tube nest therein, a floating tube sheet through which the tubes of said nest are fixed, said tube Vsheet being of a smaller diameter than the shell, a floating head of substantially the same diameter as the tube sheet and secured against the end face thereof, stud bolts screwed into the vface of the tube sheet near the edge thereof and extending through openings in said head, blind nuts threaded on to the outer ends of said bolts, said floating head being convex in section, the marginal edge thereof bearing against the face of the tube sheet along a circumferential area outside of the bolt circle, a gasket subscribing said bolts and being interposed between the contacting faces of :the floating head and the floating tube sheet, and gaskets disposed around the bolts and interposed between the floating head and the nuts. p

4. In a device of the character described, a shell having a tube nest therein, a floating tube sheet at one end of said tube nest through which the tubes of nest are fixed, a floating head of convex section secured to the end face of said floating tube sheet, said head having a marginal lip of a greater diameter than the area occupied by the tubes, and which lip is adapted to bear against the end face of the floating tube sheet along its marginal edge, fastening bolts passing through openings in the floating head and secured to the floating tube sheet, nuts on the outer ends of said bolts, circular gaskets through which the bolts extend and which gaskets are interposed between the outer face of theloating head and the nuts, and an annular gasket subscribing the fastening bolts and being interposed between the marginal lip of the floating head and the peripheral face of the floating tube sheet.

CARL F. BRAUN. 

